The present invention relates to controlling heat buildup in processors within computing systems, preferably within multiprocessor systems.
In recent years, there has been an insatiable desire for faster computer processing data throughputs because cutting edge computer applications are becoming more and more complex, and are placing ever increasing demands on processing systems. Graphics applications are among those that place the highest demands on a processing system because they require such vast numbers of data accesses, data computations, and data manipulations in relatively short periods of time to achieve desirable visual results. Real time, multimedia applications also place a high demand on processing systems; indeed, they require extremely fast processing speeds, such as many thousands of megabits of data per second.
While some processing systems employ a single processor to achieve fast processing speeds, others are implemented utilizing multi-processor architectures. In multiprocessor systems, a plurality of constituent processors can operate in parallel (or at least in concert) to achieve desired processing results.
Multiprocessor systems may be formed from processors that are manufactured separately. Under this approach, quality control systems may be used to ensure that each processor meets all pertinent standards before it is incorporated into a multiprocessor system. However, this approach is expensive as it requires a considerable number of separate manufacturing operations.
Alternatively, a multiprocessor system may be manufactured as a single integrated circuit to reduce manufacturing cost, to provide uniformity among the constituent processors, and to avoid difficulties arising from linking the various processors together once manufacturing is complete. However, such multiprocessor circuits incur the risk that a single non-performing processor within the multiprocessor circuit could cause the entire circuit to be discarded, thereby substantially reducing the overall yield of the circuits.
For example, there is a risk that one or more processors in a multiprocessor system could overheat due to the leakage current therein. Moreover, in modern processors, leakage current has tended to increase with the reduction in size and increase in number of the transistors therein. Further, leakage current increases with increasing temperature of a processor, which may lead to a self-perpetuating and uncontrollable rise in processor temperature during operation. It is therefore desirable to take measures to prevent any processor within a multiprocessor system from overheating in this manner.
There is usually variation in the leakage current among processors of any given design, owing to manufacturing process variations. Accordingly, one existing approach to preventing excessive temperatures within a multiprocessor environment is to discard high-leakage-current processors at the fabrication stage, prior to selecting processors for incorporation into a multiprocessor. While this method is effective in preventing overheating of the multiprocessor system, establishing a desirably low threshold for acceptable leakage current among the fabricated processors may result in a very low yield of useable processors.
The low-yield concern referred to above is of particular concern when the multiprocessor system is manufactured as a single integrated circuit because a single malfunctioning processor could cause an entire multiprocessor circuit to be discarded, thereby inflicting a greater burden on the overall yield than in the case where processors are manufactured independently and later incorporated into a multiprocessor system.
Accordingly, there is a need in the art to avoid the wasteful discarding of processors while still preserving the ability to prevent overheating of processors within a multiprocessor.